‘Tantalizing’ results of experiments defy the basic way physicists think

Preliminary results from two experiments suggest something could be wrong with the basic way physicists think the universe works, a prospect that has the field of particle physics baffled and thrilled.

Tiny particles called muons aren’t quite doing what is expected of them in two different long-running experiments in the United States and Europe. The confounding results — if proven right — reveal major problems with the rulebook physicists use, called the Standard Model, to describe and understand how the universe works at the subatomic level.

“We think we might be swimming in a sea of background particles all the time that just haven’t been directly discovered,” Fermilab experiment cochief scientist Chris Polly said in a press conference. “There might be monsters we haven’t yet imagined that are emerging from the vacuum interacting with our muons and this gives us a window into seeing them.”

The United States Energy Department’s Fermilab announced results Wednesday of 8.2 billion races along a track outside Chicago that have physicists astir: The muons’ magnetic fields don’t seem to be what the Standard Model says they should be.

The point of the experiments, explains Johns Hopkins University theoretical physicist David Kaplan, is to pull apart particles and find out if there’s “something funny going on” with both the particles and the seemingly empty space between them.

“The secrets don’t just live in matter. They live in something that seems to fill in all of space and time. These are quantum fields,” Kaplan said. “We’re putting energy into the vacuum and seeing what comes out.”

Both sets of results involve the strange, fleeting particle called the muon. The muon is the heavier cousin to the electron that orbits an atom’s center. But the muon is not part of the atom; it is unstable and normally exists for only two microseconds.

The experiment sends muons around a magnetized track. Preliminary results suggest that the magnetic “spin” of the muons is 0.1 percent off what the Standard Model predicts. That may not sound like much, but to particle physicists it is huge — more than enough to upend current understanding.

Researchers need another year or two to finish analyzing the results.

Separately, at the world’s largest atom smasher at CERN, several separate experiments measures what happens when particles called beauty or bottom quarks collide.

The Standard Model predicts that these beauty quark crashes should result in equal numbers of electrons and muons. It’s sort of like flipping a coin 1,000 times and getting about equal numbers of heads and tails, said Large Hadron Collider beauty experiment chief Chris Parkes.

But researchers found a 15 percent difference, with significantly more electrons than muons, said experiment researcher Sheldon Stone of Syracuse University.

Neither experiment is being called an official discovery yet because there is still a tiny chance that the results are statistical quirks.

If the results do hold, they would upend “every other calculation made” in the world of particle physics, Kaplan said.